睡眠影响记忆巩固的同步EEG-fMRI研究

The default mode network (DMN) is a brain structure persisting activity during the resting state. As resting state has been demonstrated with function of memory consolidation and sub-regions of DMN, the hippocampus and medial prefrontal cortex, are the key regions of memory consolidation, we hypothesize that the DMN is the core structure of sleep-dependent memory consolidation. With the high resolution in temporal and spatial domain of simultaneous EEG-fMRI, we will study the neural mechanisms of the DMN-involved memory consolidation, which includes: 1) describing the dynamic process of memory consolidation based on the EEG source localization and cross-frequency coupling analysis; 2) distinguishing the functional connectivity of DMN during resting and sleep states based on the sliding time-window and module analysis to reveal the basic principles of memory enhancement within the iteration of day and night; 3) revealing the influences of types of memory and sleep stages in memory consolidation by multimodel fusion. This project will not only develop new techniques for dynamic analysis of brain function, but it also has profound theory significance to elucidate the neural mechanisms of memory consolidation. Moreover it may ultimately provide new ideas for the treatment of the learning and memory related disorders.

默认网络是静息状态自发活动较强的大脑结构。它的子区域海马和内侧前额叶是记忆巩固的关键脑区，同时静息态也被证明伴随有记忆巩固现象，我们推测默认网络是睡眠依赖记忆巩固的核心。本项目拟借助同步EEG-fMRI在时空分辨率上的优势，研究默认网络参与睡眠依赖记忆巩固的神经机制。包括：1)构建默认网络活动的电生理指标，应用EEG源定位和跨频段耦合分析，揭示记忆巩固的动态过程；2)应用滑动时间窗和模块分析，研究默认网络参与静息态和睡眠过程记忆巩固的异同，揭示记忆在昼夜更迭中得以强化的基本原理；3)通过多模态信息融合，揭示记忆类型和睡眠阶段等因素对睡眠依赖记忆巩固的影响。该项目的开展将为脑功能探测开发新的动态分析技术，对阐明睡眠依赖记忆巩固的神经机制具有深刻的理论意义，并最终可能为治疗学习记忆相关障碍提供全新的思路。

本项目采用同步EEG-fMRI技术，探究了睡眠依赖记忆巩固的神经机制，并结合tDCS实现了睡眠和记忆的干预提升。首先，在动态脑网络分析方面，我们提出了EEG的全脑信号这一新指标。基于同步EEG-fMRI技术，初步证明了它和fMRI全脑信号具有类似的神经产生基础。其次，在睡眠依赖记忆巩固的影响因素方面，我们发现负性信息更难遗忘，其根本的神经机制可能在于难以激活右侧额中回。老年化也是影响记忆巩固的重要因素，老年人在睡眠缺乏情况下其睡眠依赖记忆巩固会大大受损。最后，在睡眠和记忆的神经干预方面，我们发现对额中叶的刺激可以改变决策判断，提高情绪唤醒度。对比来说，对背外侧前额叶的刺激则可以提高老年人的睡眠时长，降低默认网络和皮层下网络的连接。本项目的执行发表了SCI/SSCI检索论文18篇，获得计算机软件注册登记2项，培养硕士研究生16名，项目负责人入选国家高层次人才特殊支持计划青年拔尖人才。该项目的开展为脑功能探测开发新的分析技术，对阐明睡眠依赖记忆巩固的神经机制具有深刻的理论意义，并为老年化等引起的睡眠和记忆等问题的解决提供了全新的思路。